The Tory chairman today said "rowdy" students should not be punished by their universities even if they are recognised on TV coverage of the Millbank riot.

Baroness Warsi said rioters who committed criminal acts should be punished by the courts but it was not up to colleges to throw anyone out.

"If anybody has been caught or can be identified committing any criminal act, they need to be dealt with by the criminal law," she told the Evening Standard.

"I don't think that can be dealt with by individual colleges. If a student has been merely rowdy, well, that's just what students sometimes do."

Lady Warsi remained in her headquarters at 30 Millbank with Tory staff as the demonstration turned violent. She praised party officials for keeping their nerve when troublemakers got as far as the reception of the party's campaign HQ before being held back by security doors.

"Some members of staff went outside to protect the office by removing heavy objects that could have been used to cause damage," she said.

At one stage police said the staff should be evacuated via a back door. However, the plan was abandoned because of the troublemakers. Lady Warsi , who was trapped for four hours, said the party would review its security arrangements and added that the police should learn lessons too. "The police have said they will review things and the landlords will have to examine the security of the building," she said.

The Tories today accused a Labour MP of failing to condemn the damage to the building. Left-winger John McDonnell tweeted: "The real vandalism is not a few windows broken but £9,000 fees destroying the hopes of so many people going to university."

Conservative MP Greg Hands said: "The kind of protesting we saw was unacceptable, and no one should condone that."

Students' timetable

9.30am: Leaders of National Union of Students (NUS) and University and College Union (UCU) hold press conference at University of London union building on plans for their peaceful protest.11.30am: Around 50,000 students and lecturers assemble in Horse Guards Avenue, off Whitehall.12.30pm: Official start of the march.1.00pm: Protesters break off from march and storm Conservative Party headquarters in Millbank.1.15pm: Rally begins at Tate Britain, where organisers have no idea of the trouble a few hundred yards away.1.30pm: Thousands of protesters throw missiles at the building and try to smash windows as overstretched police struggle to hold them back.2.30pm: Riot officers arrive from the Territorial Support Group. Office staff are evacuated. Protesters light bonfire.3.30pm: Roof-top protesters booed when a metal fire-extinguisher is lobbed over the edge towards police. 4.30pm: Crowd begins to disperse but police hold those inside the building in a cordon.6.00pm: First protesters from inside Millbank building taken out in handcuffs.7.00pm: Police release protesters who have been held in cordon.